Ur-dragon, First of Many

Flying, trample, double strike, vigilance
Eminence — As long as Ur-Dragon, First of Many is in the command zone or on the battlefield, at the beginning of each player's upkeep, you may search your library for a Dragon creature card, reveal it, put it into your hand, then shuffle.

At the beginning of combat on your turn, gain control of all Dragon creatures until end of turn. Untap them. For each Dragon on the battlefield, create a 6/6 red Dragon creature token with flying and haste. Exile those